1. Field of the Invention
The present invention relates generally to barriers. More particularly, the present invention relates to fortified security gates intended to withstand vehicular impacts and a method of locking the fortified security gates.
2. Related Art
Gates used in secured areas such as prisons, airports, power plants, government facilities, research facilities, etc., must provide accessibility without diminishing security. Because of this need for accessibility, gates are often difficult to fortify or reinforce and may constitute a vulnerable spot in a perimeter security system where high powered or high speed vehicles may gain entry by impacting and knocking down the gates.
Several gates have been developed to waylay or stop vehicles attempting encroachment, thus preventing unauthorized entry into secured areas or onto barricaded portions of highway or railroad tracks. Among these are Strauss (U.S. Pat. No. 1,692,425), Orr (U.S. Pat. No. 2,023,538), Sawyer (U.S. Pat. No. 2,602,249), Buford (U.S. Pat. No. 2,189,974), and Butler (U.S. Pat. No. 4,916,859).
U.S. Pat. No. 1,692,425 to Strauss discloses a device for stopping high powered vehicles. This invention includes a liftable barrier that spans a roadway. The barrier raises vertically and remains suspended above the roadway when not in use. Furthermore, the barrier pays out when struck by a vehicle, and has a device for preventing the barrier from being lifted when the vehicle is in contact with it.
While this device is intended to stop high powered vehicles, it provides no fortification other than the gate frame itself. Furthermore, since the barrier disclosed by Strauss includes a meshed cable gate, if the invention is combined with any standard gate, the effectiveness of the system may be compromised.
U.S. Pat. No. 2,023,538 to Orr et al. discloses a mechanically operated railway crossing barrier. This invention utilizes a resilient shock absorbing bumper at each end of the gate which extends partially across the gate. However, this bumper does not span the gate, nor will it function to prevent gate failure in case of a high powered vehicular impact. Rather, it serves to protect the gate from damage in case it is accidentally bumped by a vehicle. Also, the Orr gate is not fortified against, nor intended to withstand high speed vehicular impacts. Rather, it functions to warn vehicles and block railroad crossings.
U.S. Pat. No. 2,602,249 to Sawyer discloses a yieldable barrier. This barrier provides protection for traffic at movable bridge heads, grade crossings, ferries and the like. This invention concerns an improvement and simplification of the interlocking of the movable mechanism with the structural framing which encloses and supports this mechanism. This movable mechanism carries the snubbing devices for the flexible yielding network which encloses and supports this mechanism.
This device is very similar to that disclosed by Strauss (see above), and possesses several of the same disadvantages with respect to use as a security gate system. First, it may not accommodate standard gates without compromising the strength of the system. Moreover, other than the fortification inherent in the gate and frame, it includes no additional fortification.
U.S. Pat. No. 2,189,974 to Buford discloses a highway gate having a yieldable cable arrangement so that in the event of an impact against the gate, the gate will be allowed to move a predetermined distance so as to aid in resisting the impact. This reference also discloses a gate wherein weights must be lifted when the gate is moved laterally from its normal position so that raising these weights will oppose the lateral movement of the gate and assist in bringing the impacting vehicle to rest.
As with Strauss and Sawyer (see above), the Buford gate uses a cable arrangement which pays out when impacted. Again, however, use of standard gates with this system would compromise or negate its effectiveness. Also, it discloses no additional fortification other than the gate and gate frame.
U.S. Pat. No. to Butler discloses a gate mounted on a swinging mechanism by a break away mounting. When the gate is impacted, it breaks away from the swinging mechanism and impacts a set of cushions. This device exhibits the disadvantage that the gate is never captured by the cushions and, therefore, is free to move past the cushions if enough force is applied. Further, the system of Butler is only operational with impact in a single direction.
Thus, these references disclose gates or barriers intended to withstand vehicular impacts at varying speeds. These references fail to provide gates or barriers which may be combined with standard gate systems, and which possess additional fortification aside from the gate and gate frame itself. Furthermore, these references fail Lo provide gates or barriers which provide the above functionality regardless of the direction of impact, i.e., by a vehicle. The aforementioned references are hereby incorporated by reference.